Re: [Xen-devel] is kexec on Xen domU possible?

[Matt Wilson <msw@amazon.com>]

On Mon, Jul 22, 2013 at 11:33:15AM -0700, Greg KH wrote:
> On Mon, Jul 22, 2013 at 11:24:46AM -0700, H. Peter Anvin wrote:
> > On 07/22/2013 10:20 AM, Eric W. Biederman wrote:
> > >>>
> > >>> Also, in any virtualized environment the hypervisor can do a better job
> > >>> for things like kdump, simply because it can provide two things that are
> > >>> otherwise hard to do:
> > >>>
> > >>> 1. a known-good system state;
> > >>> 2. a known-clean kdump image.
> > >>>
> > >>> As such, I do encourage the virtualization people to (also) develop
> > >>> hypervisor-*aware* solutions for these kinds of things.
> > >>
> > >> In general I agree but if you could not change hypervisor
> > >> and/or dom0 (e.g. you are using cloud providers which are
> > >> stick to old versions of Xen) then you have no choice.
> > > 
> > > Which tends to be where kexec on panic comes in most cases.  Getting
> > > platform vendors to do something sane tends to be a multi-year political
> > > effort of dubious worth while just solving the problem locally actually
> > > gets the problem solved for those who care.
> > > 
> > 
> > It should not be a "one or the other" issue.
> 
> I don't care about kdump, I care about kexec on domU for people who are
> running on cloud providers with old versions of Xen so that they can
> control what kernel they can boot, when they want to boot it.  If kdump
> works as well, that's just a bonus, but it's down on the list of things
> for me to be concerned about.

Many Xen-based cloud providers provide a mechanism for users to boot
the kernels they want. For example you can use PV-GRUB on EC2
instances to boot a kernel that is stored within an AMI.

For more info:
  http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/UserProvidedkernels.html

--msw